Previous work on this project has shown the feasibility of using noninvasive microwave transmission phase measurement to continuously monitor small changes in lung water content. The previous work included development of a new kind of microwave applicator and measurements on dogs in vivo and in isolated dog lungs. The objectives of the work proposed here are to extend the microwave methods to practical clinical use. Extensive use of a previously developed computer program will further quantify the amount of microwave phase change produced by a given change of lung water. Microwave measurements will be made simultaneously with CAT scans as pulmonary edema is induced in dogs. The data will be used in the computer program to refine the calculations and furnish the best possible methods for identifying changes in lung water from microwave measurements. Microwave measurements will then be made on renal failure patients and physically normal, schizophrenic patients during dialysis and hemofiltration. This procedure will provide an excellent human model of pulmonary edema, since the impact of removal and addition of varying amounts of fluid under closely controlled, clinically supervised conditions can be evaluated. The expected result of the proposed work is a compact, portable, practical, noninvasive microwave method for clinically monitoring small changes in total lung water content.